LED light apparatus

ABSTRACT

A LED light apparatus includes a first light source, a second light source, a PWM generator, a control signal generator and a manual switch. Users operate the manual switch to adjust a duty ratio setting of the PWM generator for adjusting a first control signal and a second control signal for controlling the first light source and the second light source to generate a desired light.

RELATED APPLICATION

The present invention is a continued application of U.S. applicationSer. No. 16/779,452, which is a continued application of U.S. patentapplication Ser. No. 16/221,445.

FIELD OF INVENTION

The present invention is related to a LED light apparatus and moreparticularly related to a LED light apparatus with variable colortemperatures.

BACKGROUND

Light apparatuses are widely used in human life. With the current LED(Light Emitted Diode) technologies, light apparatuses have much betterpower efficiency and stability compared with past light technology.

Nevertheless, light source is critical to provide living quality of anenvironment. Specifically, for different applications and differentenvironment, different light requirements may be needed to optimize thelight performance. Therefore, it is always important and helpful todiscover new needs and find a novel technology solution to solve itstechnical problems.

SUMMARY

According to an embodiment of the present invention, a LED lightapparatus includes a first light source, a second light source, a PWMgenerator, a control signal generator, and a manual switch. The firstlight source emits a first light of a first color temperature. Thesecond light source emits a second light of a second color temperature.

The PWM generator generates a PWM signal according to a duty ratiosetting for adjusting a duty ratio of the PWM signal.

Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is away of describing a digital (binary/discrete) signal that was createdthrough a modulation technique, which involves encoding a message into apulsing signal. Although this modulation technique can be used to encodeinformation for transmission, its main use is to allow the control ofthe power supplied to electrical devices, especially to inertial loadssuch as motors. In addition, PWM is one of the two principal algorithmsused in photovoltaic solar battery chargers, the other being maximumpower point tracking.

The average value of voltage (and current) fed to the load is controlledby turning the switch between supply and load on and off at a fast rate.The longer the switch is on compared to the off periods, the higher thetotal power supplied to the load.

The PWM switching frequency has to be much higher than what would affectthe load (the device that uses the power), which is to say that theresultant waveform perceived by the load must be as smooth as possible.The rate (or frequency) at which the power supply must switch can varygreatly depending on load and application, for example.

Switching has to be done several times a minute in an electric stove;120 Hz in a lamp dimmer; between a few kilohertz (kHz) and tens of kHzfor a motor drive; and well into the tens or hundreds of kHz in audioamplifiers and computer power supplies.

The term duty cycle describes the proportion of ‘on’ time to the regularinterval or ‘period’ of time; a low duty cycle corresponds to low power,because the power is off for most of the time. Duty cycle is expressedin percent, 100% being fully on. When a digital signal is on half of thetime and off the other half of the time, the digital signal has a dutycycle of 50% and resembles a “square” wave. When a digital signal spendsmore time in the on state than the off state, it has a duty cycleof >50%. When a digital signal spends more time in the off state thanthe on state, it has a duty cycle of <50%.

The main advantage of PWM is that power loss in the switching devices isvery low. When a switch is off there is practically no current, and whenit is on and power is being transferred to the load, there is almost novoltage drop across the switch. Power loss, being the product of voltageand current, is thus in both cases close to zero. PWM also works wellwith digital controls, which, because of their on/off nature, can easilyset the needed duty cycle.

The control signal generator generates a first control signal and asecond control signal based on the PWM signal. Specifically, when thefirst control signal is in a high level, the second control signal is ina low level. When the first control signal is in the low level, thesecond control signal is in the high level. In other words, the firstcontrol signal and the second control signal are kept as invertedrelation.

The first control signal is used for turning on the first light sourcewhen the first control signal is in the high level. The second controlsignal is used for turning on the second light source when the secondcontrol signal is in the high level.

The control signal generator may be made of transistor gate circuits forturning on or turning off by reference to the PWM signal. Inverter orrelated circuit components may be used for invert the PWM signal whilegenerating the first control signal and the second control signal.

The manual switch is disposed for a user to operate to change the dutyratio setting of the PWM generator for adjusting a mixed colortemperature. The manual switch may be configured by a manufacturerduring manufacturing or configured by an end user while using the LEDlight apparatus.

In some embodiments, the first light source and the second light sourceare placed in the same light source plate. For example, a circular platemay be used for mounting both the first light source and the secondlight source. To get better mixing effect, the first light source andthe second light source may be arranged alternatively or in parallel.Wires may be disposed on the light source plate. The first light sourceand the second light source may be implemented as elongated strips toemulate the appearance of traditional incandescent light. In such case,the first light source and the second light source may be disposed on anelongated substrate, e.g. in parallel to each other. The substrate maybe a rigid substrate or a flexible substrate. When the substrate is aflexible substrate, the first light source and the second light sourcemay be adjusted for their light covering angles in a three-dimensionspace.

In some embodiments, the manual switch is a mechanical switch withmultiple positions corresponding to multiple duty ratio settings to beselected by a user.

For example, there may be five positions to be selected corresponding tofive different duty ratio settings.

In some embodiments, the mechanical switch is a wheel switch.Specifically, a rotatable wheel for users to rotate to select a desiredmixed color temperature.

In some embodiments, the mechanical switch is a button for sequentiallychanging to a different duty ratio setting click by click. Specifically,each time when users press the button, a new work ratio setting isselected in a predetermined sequence.

In some embodiments, the manual switch may be a touch panel or anyelectronic style switch connecting to the PWM generator.

In some embodiments, the LED light apparatus also includes a bulb cap.The manual switch is disposed to a surface of the bulb cap.Specifically, in such case, the LED light apparatus is a light bulb. Themanual switch is exposed on the surface of the bulb cap, i.e. the bottomside for connecting to a bulb socket while still having a portionexposed to a user to operate the manual switch.

In some embodiments, the manual switch is a variable resistor supplyingdifferent resistance values corresponding to different duty ratiosettings. Certain electronic components like capacitors, resistors maybe added for supplying a status of the manual switch to the PWMgenerator.

In some embodiments, the PWM generator and the control signal generatorare integrated in an integrated circuit chip. Specifically, othercircuits like current generator may be added in the integrated circuitchip, too. In some other embodiments, these circuit components may bedistributed in multiple integrated circuit chips.

In some embodiments, the first control signal is set in the high leveland the second control signal is set in the low level when the PWMsignal is set in the high level.

In some embodiments, when the first control signal is in the high level,the first light source is turned on by supplying a first current, andwhen the second control signal is in the high level, the second lightsource is turned on by supplying a second current.

The first current and the second current may have substantially the samevalue. Specifically, a current source supplies current to both the firstlight source and the second light source. As explained above, the firstlight source and the second light source may be controlled so as notturned on at the same time, the same current source may just supply thesame current, just alternatively supplying to the first light source andthe second light source.

In some embodiments, a current source is added to the LED lightapparatus for alternatively supplying the first current and the secondcurrent to the first light source and the second light sourcerespectively.

In some embodiments, the first current and the second current areadjustable by a second switch. In other words, the duty ratio is usedfor adjusting an overall mixed color temperature. In a more complicateddesign, the first current and the second current may be further adjustedfor changing an overall luminous level of the LED light apparatus.

In some embodiments, the high level and the low level correspond to ahigh voltage level and a low voltage level respectively.

In some other embodiments, the high level and the low level correspondto a low voltage level and a high voltage level respectively.

In other words, the function mapping between the PWM signal, the firstcontrol signal and the second control signal may be chosen depending ondifferent design needs.

In some embodiments, the LED light apparatus may also include adownlight housing. The first light source and the second light sourceare disposed in the downlight housing. The manual switch is disposed ona back side of the downlight housing facing to a ceiling.

In some embodiments, the LED light apparatus may also include a thirdlight source with a third color temperature. The first light source, thesecond light source and the third light source together generate a mixedcolor temperature. For example, the third light source may be turned onor turned off, but not directly related to the first control signal orthe second control signal. The third light source may be turned onalways as a basic light source mixed with the first light source and thesecond light source to generate a desired color temperature and luminouslevel.

The present invention provides various embodiments of adjustable lightapparatuses. In first embodiment, an adjustable light apparatus includesa first light source, a second light source, a control circuit and atuning circuit. The first light source and the second light source havedifferent optical characteristic. For example, the first light sourceand the second light source have different color temperatures. Thecontrol circuit is coupled to the first light source and the secondlight source to separately turning on or turning off the first lightsource and the second light source according to control signals suppliedby the tuning circuit.

Specifically, the control circuit is coupled to the first light sourceand the second light source. The control circuit has a first controlgate and a second control gate respectively connected to a first powersource and a second power source. The first power source supplies powerto the first light source when the first control gate is turned on. Thesecond power source supplies power to the second light source when thesecond control gate is turned on. The tuning circuit have multiplesettings corresponding to different duty cycles for turning on andturning off the first control gate and the second control gate togenerate different mixing optical characteristic of the first lightsource and the second light source.

Please be noted that the first power source and the second power sourcemay be two distinct power sources but may also refer to two parts of onephysical power source. In addition, the first power source and thesecond power source may even be referred to the same power source. Inone embodiment, for example, the first light source and the second lightsource are not turned on at the same time. In other words, for anymoment, only one light source is turned on and therefore a single powersource may be used as the first power source and the second power sourcealternatingly.

In one embodiment, the first light source and the second light sourceare LED (Light Emitted Diode) modules, e.g. a LED chip or a module withmultiple LED chips. The first light source and second light source mayhave different color temperatures. By adjusting the turn-on to turn-offratio of the first light source corresponding to the second light sourcetherefore may change the visual effect of mixing color temperature.Color mixing may also be used with the technical solutions mentioned inthis disclosure.

In one embodiments, the first light source and the second light sourcerespectively have multiple LED modules arranged with an interlacedpattern to each other so that when the first light source and the secondlight source may provide a more stable mixing effect.

In one embodiment, the first control gate and the second control gateare MOSFET switches respectively receiving a first control signal and asecond control signal from the tuning circuit to turn on or to turn offthe first light source and the second light source.

In one embodiment, when the first light source is turned on, the secondlight source is turned off. In addition, when the second light source isturned on the first light source is turned off.

In one embodiment, the first control signal and the second controlsignal are PWM (Pulse Width Modulation) signals provided by the tuningcircuit. PWM, or pulse-duration modulation (PDM), is a modulationtechnique used to encode a message into a pulsing signal. The PWM signalis a series of pulses. For each pulse (i.e., each period or cycle), thepulse includes a portion of “high” signal and a portion of “low” signal.In one embodiment, the time period may be 1/1000 second between twoconsecutive high levels of the PWM signal.

In PWM case, the first control signal may refer the high level asturn-on while the second control signal may refer the low level asturn-on. In addition, the first control signal may refer the low levelas turn-off while the second control signal may refer the high level asturn-off. By disposing an inverter or related circuit, the first controlsignal and the second control signal may have the same signal source,e.g. a PWM signal. Please be noted, however, such configuration is onlyone of the methods to implement the present invention and therefore, thepresent invention is not limited by such implementation.

In one embodiment, there are more than three settings, each settingcorresponding to a different duty cycle with different turn-on byturn-off ratios for the first control signal and the second controlsignal. For example, the tuning circuit has a switch selectivelyconnected to one of five resistors to construct one of five selectiveelectrical signal values to generate a corresponding PWM signal fromfive options to control the first light source and the second lightsource. In such example, there are five settings, which means the firstlight source and the second light source may be controlled to generatefive different optical characteristics, e.g. five different colortemperatures.

In some other embodiments, the tuning of the setting may be continuous,instead of selection from several discrete options. For example, adimmer, e.g. along with an adjustable resistor, may be used to generatea corresponding voltage provided to a PWM generator to generate anassociated PWM signal over a continuous range.

In one embodiment, the adjustable light apparatus may include anoperation switch sending a tuning operation of a user to the tuningcircuit to change the mixing optical characteristic of the first lightsource and the second light source. For example, a dimmer that isoperable by a user may be used to select a setting, and the dimmer, likea rotatable button, may be connected to the tuning circuit to change thesetting of driving the first light source and the second light source.

In addition to the first light source and the second light source, inother embodiments, there may be other light sources disposed. Forexample, a third light source, or even more, may be disposed along withthe first light source and the second light source. In such case, thefirst light source, the second light source, and the third light sourcemay have different color temperatures. Under different settings, thefirst light source, the second light source and the third light sourcemay be turned sequentially with different time period ratios to generatea different overall color temperature.

In one embodiment, the adjustable light apparatus has a downlighthousing for disposing the first light source, the second light source,the control circuit and the tuning circuit. Such downlight housing mayinclude a reflector, a heat sink, a driver circuit, and othercorresponding components to be installed on a ceiling cavity. On suchhousing, there may be a mechanic switch, e.g. an adjustable lever, for auser to slide to set a corresponding setting for generating a differentoptical characteristic, e.g. a different color temperature. Suchmechanic switch may be combined with associated components to instructthe tuning circuit to change the settings of the tuning circuit.

In one embodiment, the adjustable light apparatus has a wireless circuitconnected to the tuning circuit for receiving a control instruction froman external device to change the setting of the tuning circuit. Forexample, a user may use a Wi-Fi device or a Bluetooth device on a mobilephone to send a control signal to the wireless circuit of the adjustablelight apparatus to control the tuning circuit to change a desiredsetting to get a desired overall optical characteristic of theadjustable light apparatus.

In one embodiment, the tuning circuit and the control circuit areintegrated in an integrated chip mounted on a circuit board connected toa heat sink. These circuits may generate massive heat and sucharrangement may help lengthen the life span and increase systemliability.

As mentioned above, there may be more than one optical characteristic tobe mixed. For example, the optical characteristic may include colorspectrum distribution. In other words, the first light source and thesecond light source may emit different light colors. By adjusting theirturn-on and turn-off ratio may be used to generate a different coloreffect. In addition to color, luminance strength may also be a factor tobe adjusted. For example, the first light source and the second lightsource may have different luminance levels, e.g. one emits brighter andconsumes more power than the other. By adjusting to different settings,users may easily get the desired light effect they need.

In one embodiment, the turn-on periods of the first light source and thesecond light source are partially overlapped. In such case, the firstlight source and the second light source may have a common turn-onperiod instead of a strict alternating pattern. Such design may increasea better visual effect. In such design, certain capacitor may be used tostore the increased power source to keep the overall power source notvarying too much.

In one embodiment, there may be a time gap between turn-on periods ofthe first light source and the second light source. For example, whenthe first light source is turned off, there is a time gap before thesecond light source is turned on. Such time gap may help keep the powersource stable, avoiding undesired peak to damage the power circuit.

In one embodiment, the settings are stored in a table of the tuningcircuit and the table is adjustable. For example, the tuning circuit hasa corresponding memory unit for storing optional values of the settings.A designer may change the values of the memory unit to change adifferent value. In such design, a common configuration may have betterflexibility. For example, light apparatuses sold to different regions,having different needs and requirements, may use the same hardwaresettings but loaded with different setting values.

In one embodiment, the first light source and the second light sourcemay not need to be always turned on and then turn off sequentially. Forexample, the first light source may be kept turned on. By changing theturn-on periods of the second light source, the overall opticalcharacteristic, like color temperature, may still be adjusted underdifferent settings.

In one embodiment, when one of the first light source and the secondlight source is damaged, the other light source may be kept turned on.In other words, the other light source may be used a redundant backupsolution even when one light source is damaged. In such design, anoperable switch or an automatic sensor may be used for the tuningcircuit to operate under predetermined circuit logic.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of circuit structure of a first embodimentof an adjustable light apparatus.

FIG. 2 illustrates a control timing diagram in a preferred embodimentusing PWM.

FIG. 3 illustrates a switch for providing five settings in an adjustablelight apparatus.

FIG. 4 illustrates a partial circuit diagram for implementing thecontrol and power supply functions.

FIG. 5 illustrates three different settings under PWN signals.

FIG. 6 illustrates a downlight embodiment that is adjustable.

FIG. 7A illustrates a first duty ratio diagram.

FIG. 7B illustrates a second duty ratio diagram.

FIG. 7C illustrates a third duty ratio diagram.

FIG. 8 illustrates a system diagram of an LED light apparatusembodiment.

DETAILED DESCRIPTION

Please refer to FIG. 8. FIG. 8 illustrates a system diagram of an LEDlight apparatus embodiment.

According to an embodiment of the present invention, a LED lightapparatus includes a first light source 805, a second light source 806,a PWM generator 802, a control signal generator 803, and a manual switch801. The first light source 805 emits a first light of a first colortemperature. The second light source 806 emits a second light of asecond color temperature.

The PWM generator 802 generates a PWM signal according to a duty ratiosetting for adjusting a duty ratio of the PWM signal.

Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is away of describing a digital (binary/discrete) signal that was createdthrough a modulation technique, which involves encoding a message into apulsing signal. Although this modulation technique can be used to encodeinformation for transmission, its main use is to allow the control ofthe power supplied to electrical devices, especially to inertial loadssuch as motors. In addition, PWM is one of the two principal algorithmsused in photovoltaic solar battery chargers, the other being maximumpower point tracking.

The average value of voltage (and current) fed to the load is controlledby turning the switch between supply and load on and off at a fast rate.The longer the switch is on compared to the off periods, the higher thetotal power supplied to the load.

The PWM switching frequency has to be much higher than what would affectthe load (the device that uses the power), which is to say that theresultant waveform perceived by the load must be as smooth as possible.The rate (or frequency) at which the power supply must switch can varygreatly depending on load and application, for example.

Switching has to be done several times a minute in an electric stove;120 Hz in a lamp dimmer; between a few kilohertz (kHz) and tens of kHzfor a motor drive; and well into the tens or hundreds of kHz in audioamplifiers and computer power supplies.

The term duty cycle describes the proportion of ‘on’ time to the regularinterval or ‘period’ of time; a low duty cycle corresponds to low power,because the power is off for most of the time. Duty cycle is expressedin percent, 100% being fully on. When a digital signal is on half of thetime and off the other half of the time, the digital signal has a dutycycle of 50% and resembles a “square” wave. When a digital signal spendsmore time in the on state than the off state, it has a duty cycleof >50%. When a digital signal spends more time in the off state thanthe on state, it has a duty cycle of <50%.

Please refer to FIG. 7A, FIG. 7B and FIG. 7C.

In FIG. 7A, the high level 701 of “ON” status and the low level 702 of“OFF” status occupy certain time length. In FIG. 7A, the duty ratio ofthe high level 701 to the low level 702 is 50%.

In contrast, the high level 711 of “ON” status and the low level 712 of“OFF” status in FIG. 7B show another duty ratio configuration, e.g. as75%.

In addition, the high level 721 of “ON” status and the low level 722 of“OFF” status in FIG. 7C show another duty ratio configuration, e.g. 25%.

The main advantage of PWM is that power loss in the switching devices isvery low. When a switch is off there is practically no current, and whenit is on and power is being transferred to the load, there is almost novoltage drop across the switch. Power loss, being the product of voltageand current, is thus in both cases close to zero. PWM also works wellwith digital controls, which, because of their on/off nature, can easilyset the needed duty cycle.

The control signal generator 803 generates a first control signal and asecond control signal based on the PWM signal. Specifically, when thefirst control signal is in a high level, the second control signal is ina low level. When the first control signal is in the low level, thesecond control signal is in the high level. In other words, the firstcontrol signal and the second control signal are kept as invertedrelation.

The first control signal is used for turning on the first light source805 when the first control signal is in the high level. The secondcontrol signal is used for turning on the second light source 806 whenthe second control signal is in the high level.

The control signal generator 803 may be made of transistor gate circuitsfor turning on or turning off by reference to the PWM signal. Inverteror related circuit components may be used for invert the PWM signalwhile generating the first control signal and the second control signal.

The manual switch 801 is disposed for a user to operate to change theduty ratio setting of the PWM generator 802 for adjusting a mixed colortemperature. The manual switch 801 may be configured by a manufacturerduring manufacturing or configured by an end user while using the LEDlight apparatus.

In some embodiments, the first light source and the second light sourceare placed in the same light source plate. For example, a circular platemay be used for mounting both the first light source and the secondlight source. To get better mixing effect, the first light source andthe second light source may be arranged alternatively or in parallel.Wires may be disposed on the light source plate. The first light sourceand the second light source may be implemented as elongated strips toemulate the appearance of traditional incandescent light. In such case,the first light source and the second light source may be disposed on anelongated substrate, e.g. in parallel to each other. The substrate maybe a rigid substrate or a flexible substrate. When the substrate is aflexible substrate, the first light source and the second light sourcemay be adjusted for their light covering angles in a three-dimensionspace.

In some embodiments, the manual switch is a mechanical switch withmultiple positions corresponding to multiple duty ratio settings to beselected by a user.

For example, there may be five positions to be selected corresponding tofive different duty ratio settings.

In some embodiments, the mechanical switch is a wheel switch.Specifically, a rotatable wheel for users to rotate to select a desiredmixed color temperature.

In some embodiments, the mechanical switch is a button for sequentiallychanging to a different duty ratio setting click by click. Specifically,each time when users press the button, a new work ratio setting isselected in a predetermined sequence.

In some embodiments, the manual switch may be a touch panel or anyelectronic style switch connecting to the PWM generator.

In some embodiments, the LED light apparatus also includes a bulb cap.The manual switch is disposed to a surface of the bulb cap.Specifically, in such case, the LED light apparatus is a light bulb. Themanual switch is exposed on the surface of the bulb cap, i.e. the bottomside for connecting to a bulb socket while still having a portionexposed to a user to operate the manual switch.

In some embodiments, the manual switch is a variable resistor supplyingdifferent resistance values corresponding to different duty ratiosettings. Certain electronic components like capacitors, resistors maybe added for supplying a status of the manual switch to the PWMgenerator.

In some embodiments, the PWM generator and the control signal generatorare integrated in an integrated circuit chip. Specifically, othercircuits like current generator may be added in the integrated circuitchip, too. In some other embodiments, these circuit components may bedistributed in multiple integrated circuit chips.

In some embodiments, the first control signal is set in the high leveland the second control signal is set in the low level when the PWMsignal is set in the high level.

In some embodiments, when the first control signal is in the high level,the first light source is turned on by supplying a first current, andwhen the second control signal is in the high level, the second lightsource is turned on by supplying a second current.

The first current and the second current may have substantially the samevalue. Specifically, a current source 804 in FIG. 8 supplies current toboth the first light source and the second light source. As explainedabove, the first light source and the second light source may becontrolled so as not turned on at the same time, the same current sourcemay just supply the same current, just alternatively supplying to thefirst light source and the second light source.

In some embodiments, a current source is added to the LED lightapparatus for alternatively supplying the first current and the secondcurrent to the first light source and the second light sourcerespectively.

In some embodiments, the first current and the second current areadjustable by a second switch. In other words, the duty ratio is usedfor adjusting an overall mixed color temperature. In a more complicateddesign, the first current and the second current may be further adjustedfor changing an overall luminous level of the LED light apparatus.

In some embodiments, the high level and the low level correspond to ahigh voltage level and a low voltage level respectively.

In some other embodiments, the high level and the low level correspondto a low voltage level and a high voltage level respectively.

In other words, the function mapping between the PWM signal, the firstcontrol signal and the second control signal may be chosen depending ondifferent design needs.

In some embodiments, the LED light apparatus may also include adownlight housing. The first light source and the second light sourceare disposed in the downlight housing. The manual switch is disposed ona back side of the downlight housing facing to a ceiling.

In some embodiments, the LED light apparatus may also include a thirdlight source 807 in FIG. 8 with a third color temperature. The firstlight source, the second light source and the third light sourcetogether generate a mixed color temperature. For example, the thirdlight source may be turned on or turned off, but not directly related tothe first control signal or the second control signal. The third lightsource may be turned on always as a basic light source mixed with thefirst light source and the second light source to generate a desiredcolor temperature and luminous level.

Please refer to FIG. 1, which illustrates an adjustable light apparatusembodiment. In FIG. 1, the adjustable light apparatus includes a firstlight source 101, a second light source 102, a control circuit and atuning circuit 13. The first light source 101 and the second lightsource 102 have different optical characteristic. For example, the firstlight source 101 and the second light source 102 have different colortemperatures. The control circuit is coupled to the first light source101 and the second light source 102 to separately turning on or turningoff the first light source 101 and the second light source 102 accordingto control signals supplied by the tuning circuit 13.

Specifically, the control circuit is coupled to the first light source101 and the second light source 102. The control circuit has a firstcontrol gate 111 and a second control gate 112 respectively connected toa first power source 121 and a second power source 122. The first powersource 121 supplies power to the first light source 101 when the firstcontrol gate 111 is turned on. The second power source 122 suppliespower to the second light source 102 when the second control gate 112 isturned on. The tuning circuit 13 have multiple settings corresponding todifferent duty cycles for turning on and turning off the first controlgate 111 and the second control gate 112 to generate different mixingoptical characteristic of the first light source and the second lightsource.

Please refer to FIG. 2, which illustrates control timing diagram via aPWM approach. PWM, or pulse-duration modulation (PDM), is a modulationtechnique used to encode a message into a pulsing signal. The PWM signalis a series of pulses. For each pulse (i.e., each period or cycle), thepulse includes a portion of “high” signal and a portion of “low” signal.In one embodiment, the time period may be 1/1000 second between twoconsecutive high levels of the PWM signal.

In FIG. 2, the PWM signal 210 is a square wave with a time period 201.The PWM signal has a high level 212 and a low level 211, with respect toelectrical voltage level. The PWM signal 210 is used for generating afirst control signal 230 and a second control signal 240. The firstcontrol signal 230 is used for turning on and turning off the firstlight source. The second control signal 240 is used for turning on andturning off the second light source. It is indicated in FIG. 2 that whenthe PWM signal 210 is at high level 210, the first control signal 230sends a turn-on signal 232 to turn on the first light source. When thePWM signal 210 is at low level 211, the first control signal 230 sends aturn-off signal 231 to the first light source to turn off the firstlight source. On the other hand, when the PWM signal 210 is at highlevel 210, the second control signal 240 sends a turn-off signal 242 toturn off the second light source. When the PWM signal 210 is at lowlevel 211, the second control signal 240 sends a turn-on signal 241 tothe second light source to turn on the second light source.

Please be noted that the first power source and the second power sourcemay be two distinct power sources but may also refer to two parts of onephysical power source. In addition, the first power source and thesecond power source may even be referred to the same power source. Inone embodiment, for example, the first light source and the second lightsource are not turned on at the same time. In other words, for anymoment, only one light source is turned on and therefore a single powersource may be used as the first power source and the second power sourcealternatingly.

In one embodiment, the first light source and the second light sourceare LED (Light Emitted Diode) modules, e.g. a LED chip or a module withmultiple LED chips. The first light source and second light source mayhave different color temperatures. By adjusting the turn-on to turn-offratio of the first light source corresponding to the second light sourcetherefore may change the visual effect of mixing color temperature.Color mixing may also be used with the technical solutions mentioned inthis disclosure.

In one embodiments, the first light source and the second light sourcerespectively have multiple LED modules arranged with an interlacedpattern to each other so that when the first light source and the secondlight source may provide a more stable mixing effect.

In one embodiment, the first control gate and the second control gateare MOSFET switches respectively receiving a first control signal and asecond control signal from the tuning circuit to turn on or to turn offthe first light source and the second light source.

In one embodiment, when the first light source is turned on, the secondlight source is turned off. In addition, when the second light source isturned on the first light source is turned off.

In one embodiment, the first control signal and the second controlsignal are PWM (Pulse Width Modulation) signals provided by the tuningcircuit.

In PWM case, the first control signal may refer the high level asturn-on while the second control signal may refer the low level asturn-on. In addition, the first control signal may refer the low levelas turn-off while the second control signal may refer the high level asturn-off. By disposing an inverter or related circuit, the first controlsignal and the second control signal may have the same signal source,e.g. a PWM signal. Please be noted, however, such configuration is onlyone of the methods to implement the present invention and therefore, thepresent invention is not limited by such implementation.

In one embodiment, there are more than three settings, each settingcorresponding to a different duty cycle with different turn-on byturn-off ratios for the first control signal and the second controlsignal. For example, the tuning circuit has a switch selectivelyconnected to one of five resistors to construct one of five selectiveelectrical signal values to generate a corresponding PWM signal fromfive options to control the first light source and the second lightsource. In such example, there are five settings, which means the firstlight source and the second light source may be controlled to generatefive different optical characteristics, e.g. five different colortemperatures.

Please refer to FIG. 3, which illustrates a portion of a driving circuitin a light apparatus. Since persons of ordinary skilled in the art knowhow to implement a common light apparatus driver, common circuits arenot mentioned here for simplicity.

In FIG. 3, the switch 31, which may be a digital or a mechanical devicefor selectively connecting to five different resistors 301, 302, 303,304, 305 to generate different signal value to supply to a tuningcircuit 32.

FIG. 4 illustrates a circuit example, not to limit the present inventionbut used for explaining at least one way to implement the inventiveconcept.

In FIG. 4, several passive components 401, 402, 403, 404, 405, 406 areused together with two MOSFET gates 41 and 42. The two MOSFET gates 41,42 receives two control signals 411, 421, as mentioned above to turn onor turn off power source to a first light source and a second lightsource. In FIG. 4, the nodes 431, 432 are selectively connected to 433to select one of the first light source and the second light source toget power supply to turn on. The circuits in FIG. 4 is further connectedto other portion of a driver circuit 45 to complete the drivingfunction.

Please refer to FIG. 5, which illustrate three settings in a PWM drivenexample of an adjustable light apparatus.

In FIG. 5, three PWM signals 501, 502, 503 having different high levelto low level ratios. As mentioned above, such settings may causedifferent turn-on ratios between the first light source and the secondlight source.

Please be noted that the example is not used to limit the presentinvention. Persons of ordinary skilled in the art may amend the designfor implementing the present invention. For example, turn-on andturn-off switching between the first light source and the second lightsource may depend on rising and falling edges of a periodic signal.Alternatively, the numbers of a periodic wave may be allocatedrespectively to turn on the first light source and the second lightsource. Specifically in such example, two high levels may be allocatedto turn on the first light source while another consecutive four highlevels may be allocated to turn on the second light source. Othervariations, under such teaching, are supposed to be understood andenabling for persons of ordinary skilled in the art.

In some other embodiments, the tuning of the setting may be continuous,instead of selection from several discrete options. For example, adimmer, e.g. along with an adjustable resistor, may be used to generatea corresponding voltage provided to a PWM generator to generate anassociated PWM signal over a continuous range.

In one embodiment, the adjustable light apparatus may include anoperation switch sending a tuning operation of a user to the tuningcircuit to change the mixing optical characteristic of the first lightsource and the second light source. For example, a dimmer that isoperable by a user may be used to select a setting, and the dimmer, likea rotatable button, may be connected to the tuning circuit to change thesetting of driving the first light source and the second light source.

In addition to the first light source and the second light source, inother embodiments, there may be other light sources disposed. Forexample, a third light source, or even more, may be disposed along withthe first light source and the second light source. In such case, thefirst light source, the second light source, and the third light sourcemay have different color temperatures. Under different settings, thefirst light source, the second light source and the third light sourcemay be turned sequentially with different time period ratios to generatea different overall color temperature.

In one embodiment, the adjustable light apparatus has a downlighthousing for disposing the first light source, the second light source,the control circuit and the tuning circuit. Such downlight housing mayinclude a reflector, a heat sink, a driver circuit, and othercorresponding components to be installed on a ceiling cavity. On suchhousing, there may be a mechanic switch, e.g. an adjustable lever, for auser to slide to set a corresponding setting for generating a differentoptical characteristic, e.g. a different color temperature. Suchmechanic switch may be combined with associated components to instructthe tuning circuit to change the settings of the tuning circuit.

Please refer to FIG. 6, which illustrates a downlight device as anembodiment of the present invention. In FIG. 6, an lever 631 may bemoved by a user to change the setting of the tuning circuit 62 to changehow to switch between a first light source 631 and a second light source632.

In one embodiment, the adjustable light apparatus has a wireless circuitconnected to the tuning circuit for receiving a control instruction froman external device to change the setting of the tuning circuit. Forexample, a user may use a Wi-Fi device or a Bluetooth device on a mobilephone to send a control signal to the wireless circuit of the adjustablelight apparatus to control the tuning circuit to change a desiredsetting to get a desired overall optical characteristic of theadjustable light apparatus.

In one embodiment, the tuning circuit and the control circuit areintegrated in an integrated chip mounted on a circuit board connected toa heat sink. These circuits may generate massive heat and sucharrangement may help lengthen the life span and increase systemliability.

As mentioned above, there may be more than one optical characteristic tobe mixed. For example, the optical characteristic may include colorspectrum distribution. In other words, the first light source and thesecond light source may emit different light colors. By adjusting theirturn-on and turn-off ratio may be used to generate a different coloreffect. In addition to color, luminance strength may also be a factor tobe adjusted. For example, the first light source and the second lightsource may have different luminance levels, e.g. one emits brighter andconsumes more power than the other. By adjusting to different settings,users may easily get the desired light effect they need.

In one embodiment, the turn-on periods of the first light source and thesecond light source are partially overlapped. In such case, the firstlight source and the second light source may have a common turn-onperiod instead of a strict alternating pattern. Such design may increasea better visual effect. In such design, certain capacitor may be used tostore the increased power source to keep the overall power source notvarying too much.

In one embodiment, there may be a time gap between turn-on periods ofthe first light source and the second light source. For example, whenthe first light source is turned off, there is a time gap before thesecond light source is turned on. Such time gap may help keep the powersource stable, avoiding undesired peak to damage the power circuit.

In one embodiment, the settings are stored in a table of the tuningcircuit and the table is adjustable. For example, the tuning circuit hasa corresponding memory unit for storing optional values of the settings.A designer may change the values of the memory unit to change adifferent value. In such design, a common configuration may have betterflexibility. For example, light apparatuses sold to different regions,having different needs and requirements, may use the same hardwaresettings but loaded with different setting values.

In one embodiment, the first light source and the second light sourcemay not need to be always turned on and then turn off sequentially. Forexample, the first light source may be kept turned on. By changing theturn-on periods of the second light source, the overall opticalcharacteristic, like color temperature, may still be adjusted underdifferent settings.

In one embodiment, when one of the first light source and the secondlight source is damaged, the other light source may be kept turned on.In other words, the other light source may be used a redundant backupsolution even when one light source is damaged. In such design, anoperable switch or an automatic sensor may be used for the tuningcircuit to operate under predetermined circuit logic.

In addition to the above-described embodiments, various modificationsmay be made, and as long as it is within the spirit of the sameinvention, the various designs that can be made by those skilled in theart are belong to the scope of the present invention.

The invention claimed is:
 1. A LED light apparatus, comprising: a firstlight source for emitting a first light of a first color temperature; asecond light source for emitting a second light of a second colortemperature; a PWM generator for generating a PWM signal according to aduty ratio setting for adjusting a duty ratio of the PWM signal; acontrol signal generator for generating a first control signal and asecond control signal based on the PWM signal, wherein when the firstcontrol signal is in a high level, the second control signal is in a lowlevel, the first control signal is used for turning on the first lightsource, and the second control signal is used for turning on the secondlight source; and a manual switch with more than two options for a userto select one of the options to change the duty ratio setting of the PWMgenerator for adjusting a mixed color temperature; and a current sourcefor supplying a first current and a second current to the first lightsource and the second light source respectively.
 2. The LED lightapparatus of claim 1, wherein the first light source and the secondlight source are placed in the same light source plate.
 3. The LED lightapparatus of claim 1, wherein the first light source and the secondlight source are disposed on at least one elongated substrate.
 4. TheLED light apparatus of claim 3, wherein the elongated substrate isflexible.
 5. The LED light apparatus of claim 1, wherein the manualswitch is a mechanical switch with multiple positions corresponding tomultiple duty ratio settings to be selected by a user.
 6. The LED lightapparatus of claim 5, wherein there are five positions to be selectedcorresponding to five different duty ratio settings.
 7. The LED lightapparatus of claim 5, wherein the mechanical switch is a wheel switch.8. The LED light apparatus of claim 5, wherein the mechanical switch isa button for sequentially changing to a different duty ratio settingclick by click.
 9. The LED light apparatus of claim 5, furthercomprising a bulb cap, and wherein the manual switch is disposed to asurface of the bulb cap.
 10. The LED light apparatus of claim 5, whereinthe manual switch is a variable resistor supplying different resistancevalues corresponding to different duty ratio settings.
 11. The LED lightapparatus of claim 1, wherein the PWM generator and the control signalgenerator are integrated in an integrated circuit chip.
 12. The LEDlight apparatus of claim 1, wherein the first control signal is set inthe high level and the second control signal is set in the low levelwhen the PWM signal is set in the high level.
 13. The LED lightapparatus of claim 1, wherein when the first control signal is in thehigh level, the first light source is turned on by supplying the firstcurrent, and when the second control signal is in the high level, thesecond light source is turned on by supplying the second current. 14.The LED light apparatus of claim 13, wherein the first current and thesecond current has substantially the same value.
 15. The LED lightapparatus of claim 1, wherein a user operates a remote device to selectthe option sent to the PWM generator.
 16. The LED light apparatus ofclaim 13, wherein the first current and the second current areadjustable by a second switch.
 17. The LED light apparatus of claim 1,wherein the high level and the low level correspond to a high voltagelevel and a low voltage level respectively.
 18. The LED light apparatusof claim 1, wherein the high level and the low level correspond to a lowvoltage level and a high voltage level respectively.
 19. The LED lightapparatus of claim 1, further comprising a downlight housing, whereinthe first light source and the second light source are disposed in thedownlight housing and the manual switch is disposed on a back side ofthe downlight housing facing to a ceiling.
 20. The LED light apparatusof claim 1, further comprising a third light source with a third colortemperature, wherein the first light source, the second light source andthe third light source together generate a mixed color temperature.